Trimethine cyanine dyes



Patented Feb. 23, 1937 UNITED STATES TRIMETHINE CYANINE' DYES WalterZelnDessau in Anhalt, Willi Gaedke, Hofheim in Taunus, Martin Dabelow,Frankforton-the-Main-Hochst,

and Werner Zerweck,

Frankfort-on-the-Main-Fechenheim, Germany, assignors 'to Agfa AnscoCorporation, Binghamton, N. Y., a corporation o f'N ewYork No Drawing.Original application July 8, 1932,

Serial No. 621,474. Divided. and this applica- .tion. February 19, 1934,Serial'No. 712,072. In

Germany July 11, 1931 3 Claims.

Our present invention relates to the manufacture of dyes of the cyanineseries. .It is a division of our co-pending application Ser. No.621,474, filed July 8,1932.

One of its objects is to provide cyanine dyes in which twothiazolenuclei having fused on a condensed; ring. system of more, than 2 nucleiare linked together by a tri-methenyl chain. Further objects will beseen from the detailed specifition following. hereafter.

We have found that the thiazole-trimethinecyanines which are derivedfrom higher polynuclear cyclic. compounds are well suitable forsensitizing a. silver halide. emulsion to red and have over the hithertoknown carbocyanines the advantage of a higher intensity in the spectralred.

As asstarting material for the new sensitizing dyestufis there maybeused the 2-methyl-thiazole Anthtacene Phenantrene Acenaphthena FluoreneOhrysene Carbazole Diphenylene-onde The dyestufis are obtainableanalogous to known methods. In order to prepare, for instance,.theanthrathiocarbocyanines, one starts flOllLaor ,B-athramine and, by wayof its acetyland' 'thioacet-compound' the Z-methylanthrathiazole isobtainable by oxidation with potassium ferricyanida' By treating theZ-methylanthrathiazole with diethylsulfate or ethyltoluenesulfonate inknown manner it is transformed into the quaternary compound which isthen condensed in anhydrous pyridine to a trimethinecyanine by means ofa trialkylorthocarboxylic acid ester. When condensing anthrathiazolewith an alkylorthoformic ester; there are obtained trimethinecyanines ofthe following formulae (whereinR stands for an alkyl radical and Xior ananion):

B-compound If the condensation iscarried out with the ester of a higherorthocarboxylic acid, the hydrogen of the central C-atom of the chain issubsituted by an alkyl group. The dyestuffs substituted in this mannerpossess a more intensive sensitizing action, the compounds having ahydroxyalkyl *substituent showing a better solubility in water.

The scope of the invention is intended to include also such dyestuffs asare substituted in any manner in the anthracene-phenanthreneetc. ringsor in which the sulphur of the thiazole ring has been replaced byoxygen, or selenium.

The following examples serve to illustrate our invention more clearly.stance the manufacture of the bases our sensitizers are made from, themethod of preparation being like that of the dyes analogous to knownmethods. Examples 3 to 8 demonstrate the manufacture of the dyes whenstarting from the bases.

Example 1.--2-methyl-carbazolethiazole is prepared as follows:

9-benzoyl-3-aminocarbazole (melting point 148 to 150 C.) is transformedinto 9-benzoyl-2- aminothiazole according to the process described inGerman specification 491,223. Said compound forms colorless needleshaving a melting point of 280 C. when recrystallized from glacial aceticacid. After cleaving the molecule according to the method indicated inGerman specification 495,102 o-mercapto-3-amin0carbazole is obtained,the benzoyl residue being split off at the same time. The compound ispreferably separated in form. of the zinc mercaptide. By heating theproduct with acetic anhydride and glacial acetic acid the2-methylthiazole is obtainable,

corresponding probably with the following formula I l N s l on.

and forming when recrystallized from diluted alcohol colorless crystalswhich melt at 165 C.

Example 2.For producing Z-methyl-diphenylene-oxide-thiazole2-amino-diphenyleneoxide is according to the method described in Germanspecification 491,223 made into the amino-thiazole which crystallizesfrom hot diluted hydrochloric acid as the chloride. By cleaving themolecule in an alkaline medium according to the method described inGerman specification 495,102 the o-mercapo-2-aminodiphenylene-oxide isseparated in form of its zinc mercaptide. When heated with aceticanhydride and glacial acetic acid this compound yields the2-methyl-thiazole corresponding probably with the following fomula:

S NJ-CHa and forming when recrystallized from diluted alcohol glitteringcrystals which melt at 162 C.

Example 3.The dye bis-i 3-ethyl-[anthraceno-2.1':4.5-thiazolel:(2)}-,B-ethyl-trimethine- Examples 1 and 2 incyanine bromide correspondingprobably with the formula:

5 EZHB is obtained by heating 5 grams of2-methyl-fianthrathiazole-diethylsulfate in 10 cc. of dry pyridine with5 cc. of ethyl-ortho-propionate for about hour to about 130 C. Hereonthe dye is precipitated by addition of about cc. of a 5 per centsolution of potassium bromide. By recrystallization from methanol ablackish-green crystal powder is obtainable.

The alcoholic solution of the dye has an absorption maximum at a wavelength of about 610,LL}L.

Example 4.-The dye bis- {3-ethyl-[anthraceno-l' .2 :4.5-thiazolel (2)-/8-ethy1-trimethinecyanine bromide is produced by starting from 2-methyl-a-anthrathiazole-diethylsulfate, the reaction and the conditionsbeing the same as in Example 3.

Example 5.The dye bis-{ 3-ethyl- [carbazolo- 3'.2' 4.5-thiazole] (2)-trimethinecyanine chloride corresponding with the formula:

is obtainable as follows:

5 grams of 2-methylcarbazole-diethyl-sulfate are heated with 3 cc. ofethyl-ortho-formate in 10 cc. of pyridine for about 1 hours to C. On theaddition of sodium chloride the dye precipitates from the blue solution.Recrystallization from methanol yields green little rods.

The alcoholic solution of the dye shows an absorption maximum at a wavelength of about 605jL/L.

Example 6.The dye bis-{ 3-ethyl-[acenaphtheno 5'.4: 4.5-thiazole] (2)3-methyl trimethine cyanine bromide corresponding with the formula isobtainable by heating 3 grams of 5-methylacenaphthenethiazole-diethylsulfate in 10 cc. of dry pyridine with 3 cc. ofethyl-ortho-acetate for about hour to 130 C. The dye is precipitated byadding to the reaction mixture about 100 cc. of a 5 per cent solution ofpotassium bromide. After recrystallization from methanol it forms smallblue needles which are felted.

The alcoholic solution of the dye has an absorption maximum at about 585l.

Example 7.The dye bis-{ 3-methyl-[diphenyleneoxide 2.3' 14.5 thiazole](2) -fi-methy1- trimethinecyanine chloride corresponding with theformula:

may be produced by heating 2.5 grams of diphen- .lyeneoxideZ-methylthiazole and 4 cc. of ethylortho-acetate with 10 cc. of pyridinefor about /2 hour to C. The dye which precipitates already during theheating operation in form of its sulfalkylate is separated from themother liquid by suction. The dye is then dissolved in methanol andprecipitated by addition of a 10 per cent solution of common salt.

The alcoholic solution of the dye shows an absorption maximum at a wavelength of about 585 141 It is to be understood that our invention is notlimited to the foregoing examples or to the specific details giventherein. Numerous other embodiments are possible and we contemplate asincluded within our invention all such modifications and equivalents asfall Within the scope of the appended claims. So, for instance thedifferent nuclei may contain one or more substituents. The formulae ofthe dyes as given therein represents the molecular structure of our newdyes so far as known. If, however, in future it should become evidentthat the formulae do not exactly correspond to the dyes this fact willnot affect our invention since the dyes will be easily identified by themethod of producing the same which has been fully described in theexamples and is analogous to known methods.

What we claim is:

1. Bis 3-ethy1-[carbazo1o 3'2-4.5 thiazolel- (2) 1trimethinecyamine-chloride corresponding probably with the formula 3. Abis-{ 3-alky1-[carbazolo thiazolel-(Z) p-alkyl-trimethine-cyanine salt.

WALTER ZEH. WILLI GAEDKE. MARTIN DABELOW. WERNER ZERWECK.

